Movie clip editor playback problem
I'm going to take a guess and say that your video is somehow corrupt, or you are dealing with issues with a delivery codec, meaning a highly compressed video files that use long GOP compression. Let me guess: h264, mp4, mts, AVC or AVCHD... or if we are talking about something recorded from a computer game... could be that you have one of those horrible videos that uses variable frame rate...

In any case there are a couple of solutions.

If your system has plenty of RAM, increase the cache size on the system preferences>System>Sequencer/Clip Editor>Memory Cache Limit.

Other thing to do is to transcode your video to an image sequence and use that to track instead.